This invention relates to continuous yarn winding equipment and particularly to auxiliary apparatus to apply a substantially constant force between a winding package and a drive roll during the formation of the package and to release this force during doffing. By doffing is meant the several steps of bringing an empty yarn package support into engagement with the windup drive roll, moving the full package of yarn away from the drive roll and transferring the yarn from winding on the full to the empty package support and removing the full package.
Satisfactory high speed yarn winding has been achieved by various winding machines such as those described by De Priest in U.S. Pat. No. 3,165,274, by Smiley in U.S. Pat. No. 3,342,428 and by Campbell et al. in U.S. Pat, No. 3,409,238. However, to provide for overend delivery of yarn from packages wound of spandex yarn, it has been found desirable to employ a large contact force between the package and the drive roll during package formation and to maintain this force constant from initial yarn laydown on a package support up until a full yarn package has been produced. Since the doffing cycle is carried out by manual manipulation of the full and empty yarn package chucks, it is desirable to eliminate this force between the package and drive roll while doffing to reduce operator fatigue and assist his successful completion of the exacting no-waste yarn transfer procedure. It has also been found important in some cases to provide fine adjustment of the magnitude for this constant force before starting a new package.
Various adjustable (but nonconstant) counterweight arrangements have been employed in the past to provide force between package and drive roll. However, these arrangements have not been readily modified to provide a substantially constant, preselected force during the full winding cycle and a releasable force during doffing.